1. Field of the Invention
The present invention is in the field of automatic processors for lithographic plates. More particularly, this invention is in the field of automatic processors for plates for waterless lithographic printing.
2. Description of the Prior Art
Machines for the automatic processing of lithographic plates are known in the art. Such machines effect various kinds of actions on the surface of the plate, including washing, scrubbing and gum application. Earlier machines have been large, complicated and heavy, but more modern developments have tended toward lighter and more versatile processors.
Among the lighter machines are included the apparatus described in U.S. Pat. No. 3,983,758 to Hovekamp, assigned to the assignee of the present invention. Hovekamp describes a processor which sequentially develops, washes and applies gum to an exposed offset lithographic plate yet is small enough to fit through a standard one-meter-wide doorway, and is sufficiently simple mechanically to permit personnel without extensive training to service such machines.
In recent time, there has been developed a plate for offset lithography which permits printing to be done without the need for water in the process. Such a plate has a transparent protecting film over a silicone polymer which in turn overlies a photosensitive layer. The balance of the plate is similar to existing lithography plates, and exposure of the plate in preparation for subsequent printing is the same as with prior-art plates.
In the processing of the exposed waterless plate, a different series of steps from that now used in the art is required. Machinery is available to do this function, but a lower-cost, more easily maintainable machine is desirable.